Questions & Answers about Režem mrkvu za juhu, ali nož je tup.
Režem is the present tense, 1st person singular form of the verb rezati (to cut).
The ending -em is common in present-tense forms of many verbs (though conjugation patterns vary). Here it marks I as the subject.
Rezati / režem is imperfective, focusing on the process (cutting as an ongoing activity). That fits a context like I’m cutting a carrot for soup….
A perfective partner is often narezati (to cut up/slice up completely). For a completed result you might say Narezao/narezala sam mrkvu (I cut up the carrot).